In a mobile communication system being studied as Evolved universal terrestrial radio access network (E-UTRAN), a mobile station is configured to transmit a connection request to a certain cell, when communicating with the certain cell, and when detecting the same cell as the certain cell for a certain time period after failing to detect a radio link between the mobile station and the certain cell (a radio link failure) (see Non-patent Document 1).
Meanwhile, when a mobile station performs a handover between radio base stations, a handover source radio base station transfers mobile station information including TMSI (temporary mobile subscriber identity) to a handover destination radio base station.
Here, when the radio base station having received the above-mentioned connection request determines that the TMSI included in the above-mentioned connection request exists in mobile station information that the radio base station manages, then the radio base station allows the mobile station to continue communication, by use of the mobile station information that the radio base station manages.
On the other hand, when the radio base station determines that the TMSI included in the above-mentioned connection request does not exist in the mobile station information that the radio base station manages, the radio base station determines that the connection request is a new connection request, and performs a new connection setting process.
Under such control, the mobile station is allowed to continue communication, not only when the certain cell with which the mobile station is communicating is the same as the cell detected by the mobile station, but also when the certain cell with which the mobile station is communicating and the cell detected by the mobile station are encompassed by the same radio base station (see Non-patent Document 2).
Meanwhile, in the conventional mobile communication system, a mobile switching center (MME: Mobility Management Entity) manages location information of each of mobile stations either in Idle or in Active, and allocates TMSIs to the mobile stations, the TMSIs uniquely identifying the respective mobile stations within the mobile switching center (see Non-patent Document 3).
Then, when a mobile station travels beyond a mobility management area (pool area) managed by the mobile switching center, the mobile switching center relocates the mobile station information for the mobile station to the newly visited mobile switching center (MME relocation), and the TMSI uniquely identifying the mobile station within the newly visited mobile switching center is reallocated to the mobile station.    Non-patent Document 1: 3GPP 36.300 V8.0.0 Technical specification group radio access network; Evolved universal terrestrial radio access (E-UTRA) and Evolved universal terrestrial radio access network (E-UTRAN); Overall description; Stage 2, 10.1.6    Non-patent Document 2: 3GPP R2-071229, “Radio link failure and context recovery”, Nokia    Non-patent Document 3: 3GPP 24.801 V0.1.0 Technical specification group core network and terminals; 3GPP system architecture evolution; CT WG1 aspects (Release 8), 5.3